ABSTRACT Three hundred and fifty broiler chickens (Anak, 2000) were used to study the effect of partial replacement of soya bean meal (SBM) protein with cassava and or leucaena leaf meals. Diet 1 was the control diet with soyabean meal but no leaf meal. Diets 2 and 3 had 30% and 60% SBM protein respectively replaced with cassava leaf meal (CLM) protein. In diets 4 and 5, 30% and 60% of the SBM protein respectively, were replaced with leucaena leaf meal (LLM) protein. The SBM protein in diets 6 and 7 was substituted at 30% and 60% respectively with 50:50 CLM and LLM protein. The birds were assigned to the experimental diets at 10 birds per replicate and 5 replicates per treatment. The energy to protein ratios of the diets were similar. The response criteria measured were feed intake, weight gain, nitrogen retention, shank and skin pigmentation, selected carcass, organ and muscle characteristics and economics of production. The results showed that weight gain (WG, 52.1Ã‚Â±1.00 g/day) and feed intake (134Ã‚Â±4.37 g/day) were higher (P<0.05) in birds fed the control diets. On other diets, WG were 44.4Ã‚Â±4.18 g (Diet 2), 43.7Ã‚Â±2.10 g (Diet 6), 40.2Ã‚Â±4.32 g (Diet 4), 37.2Ã‚Â±4.13 g (Diet 3), 34.9Ã‚Â±1.04 g (Diet 7) and 26.0Ã‚Â±4.86 g (Diet 5) per day. Nitrogen retention was apparently highest (P>0.05) for birds on the control diet. Shanks of birds on leaf meal diets were more pigmented (P<0.05) than the control. Carcass, organ and muscle characteristics were not affected (P<0.05) by dietary treatments. Cost of feed per kilogram weight gain were similar for broiler on Diets 1, 2 and 6 ( 110, 108 and 109 respectively) and highest for Diet 5 ( 150). It was concluded that 30% replacement of soyabean meal protein in a 14% soyabean meal ration with cassava (10.50% of diet) or 50:50 cassava and leucaena (9.55% of diet) leaf meal protein would optimize growth performance and economic returns from broiler production especially during periods of high cost and scarcity of soyabean meal.